Ice loss from Greenland’s glaciers may level off

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The increasing pace of ice breaking off Greenland’s glaciers and dumping into the ocean may not actually be a warning sign of runaway ice loss and catastrophic sea level rise, researchers report in the May 9 Nature.

Greenland’s ice sheet raises sea level when the surface melts or when glaciers flow into the sea and discharge icebergs. Scientists have been concerned that the last decade’s acceleration in iceberg calving would continue unchecked. Simulations have been unable to verify or refute those fears because it’s difficult to account for all of the processes, such as warm seawater’s melting of a glacier’s base, that influence how the streams of ice move and shed icebergs.

Now, Faezeh Nick of the Université Libre de Bruxelles in Belgium and colleagues have incorporated all of these variables into a simulation that predicts the activity of four of Greenland’s main glaciers. In a scenario where global temperatures warm 2.8 degrees Celsius by 2100, the glaciers’ rate of ice loss eventually levels off, the simulation suggests. In total, the four glaciers could raise sea level by about 1 centimeter by 2100.

Applying the findings to the rest of the island’s glaciers, the researchers predict Greenland could add as much as 18.3 centimeters to sea level by the end of the century. That amount is about 35 centimeters less than a previous estimate that extrapolated Greenland’s current ice loss acceleration into the future.

An iceberg calves off Greenland’s Jakobshavn Glacier on May 10, 2008. In this time-lapse video, photos were taken every 10 seconds for an hour.
Credit: Jason Amundson, Martin Truffer and Mark Fahnestock/Univ. of Alaska Fairbanks